In general, an elongated trim is mounted on a flange of a door opening fringe or an opening fringe of a trunk or hatchback of a vehicle such as car along the flange. The trim is extruded in a shape having a mounting portion which is substantially U-shaped in cross section, using a polymer material such as rubber or thermoplastic synthetic resin including thermal plastic elastomer. The U-shaped mounting portion interposes the flange of the opening fringe from both sides such that the trim is fixed to the flange. In such a trim, an elongated reinforcing core (for example, a core formed of a strip-shaped metal plate such as a cold rolled steel plate) having a U-shaped cross section corresponding to the mounting portion is buried and integrated in the mounting portion. Then, the core reinforces the mounting portion such that the mounting portion is stably fixed to the flange of the opening fringe.
However, the flange of a door opening fringe or the opening fringe of a trunk or hatchback of a vehicle is two- or three-dimensionally bent in the longitudinal direction. Therefore, the trim formed in a substantially straight line shape by extrusion molding is mounted so as to be bent in accordance with the bending shape of the flange of the opening fringe. Accordingly, a core having a plurality of spaces formed at predetermined intervals in the longitudinal direction is used as the core buried in the trim. The core is flexibly bent in accordance with the bending of the trim. The core may include a fish-bone core and a keel core.
Parts used in a vehicle such as a car require a reduction in weight. When the thickness of the core is simply decreased to reduce the weight of a trim, the rigidity of the core may be degraded. Therefore, when a trim having a core buried therein is mounted on the flange of an opening fringe, the holding force of the trim is reduced, by which the flange is interposed and held. The trim may not be stably fixed to the flange.
As disclosed in Patent Documents 1 to 3, a plurality of gaps (or slits) are punched and formed at predetermined intervals in a longitudinal direction of a strip-shape metal plate by pressing to form an insert for the trim in which core pieces and gaps (or slits) are alternately provided in the longitudinal direction. As deformed portion (or convex portion) is press-molded in the core piece at the same time when the gaps (or slits) are punched and formed in the strip-shaped metal plate by pressing, the rigidity of the insert for trim is secured by the deformed portion (or convex portion) and the thickness of the insert for trim is reduced. Then, the holding force of the trim may be secured and the trim is reduced in weight.
However, when the gaps (or slits) are punched and fanned in the strip-shaped metal plate by pressing, defects may occur because the punched portion of the strip-shaped metal plate becomes unnecessary. Then, yield may decrease.
Patent Document 4 discloses a strip-shaped insert in which cut lines are formed at a predetermined pitch in both widthwise sides of the strip-shaped insert in the longitudinal direction thereof, and then rolled and extended in the longitudinal direction to form slits at predetermined intervals.    [Patent Document 1] JP-A-2004-9355    [Patent Document 2] JP-A-2005-14792    [Patent Document 3] JP-A-2008-230448    [Patent Document 4] JP-A-7-117577
As described in Patent Document 4, even when a portion of the strip-shaped insert in which the cut lines are not formed is rolled to form the insert provided with slits, deformed portions (or convex portions) are press-molded in the insert by pressing, after the portion of the strip-shaped insert in which the cut lines are not formed is rolled to form the insert provided with slits by using the techniques of Patent Documents 1 to 3 in which the deformed portion (or convex portion) is press-molded in the insert by pressing. Therefore, the rigidity of the insert is secured by the deformed portion (or convex portion) and the thickness of the insert is reduced.
However, when the deformed portion (or convex portion) is press-molded by pressing, the supply (transfer) of the insert needs to be temporarily stopped at each press-molding timing of the deformed portion (or convex portion). Therefore, the deformed portion (or convex portion) may be not efficiently formed in the insert. Therefore, when the insert is continuously transferred and supplied and the deformed portion (or convex portion) is press-molded in synchronization with the extrusion molding of the trim in a trim manufacturing line, the trim may not be efficiently manufactured.
Additionally, when the portion of the strip-shaped insert in which the cut lines are not formed is rolled to form the insert provided with slits, deviations may occur in the length of the slits (the dimension of the slits in the longitudinal direction of the insert) due to deviations in the thickness or composition of the metal material in the rolled portion. Then, a deviation may occur in the gap between the core pieces formed between the slits. Therefore, when the deformed portion (or convex portion) is press-molded by pressing, a deviation may occur in the formation position of the deformed portion (convex portion) with respect to the core piece in the longitudinal direction of the insert, and a core piece in which the deformed portion (or convex portion) is partially formed may be formed. Accordingly, it is difficult to sufficiently secure rigidity by the deformed portion (convex portion), and deviation occurs in the rigidities of the respective core pieces.